body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  background: linear-gradient(135deg,#f5f7fa,#c3cfe2);
  color:#222;
  margin:0;
  height:100vh;
  display:flex;
  align-items:center;
  justify-content:center;
}
.center {
  text-align:center;
  padding:2rem;
  background:rgba(255,255,255,0.8);
  border-radius:12px;
  box-shadow: 0 6px 18px rgba(34,34,34,0.08);
  max-width: 680px;
}
h1 { margin:0 0 0.5rem 0; font-size:2.25rem; }
.lead { margin:0 0 1rem 0; color:#444; }
.muted a { color:#1e88e5; text-decoration:none; }